Another "not a nit, more an observation". Based on their performance in this episode, I can't believe the station crew could ever find a Founder infiltrator, let alone do it in a few hours. They really need some way of spotting them with sensors, rather than just blasting everything in sight with phasers.

Here's a nit, though. When the Defiant cloaks, Worf looks a bit uncomfortable and explains that "I have never been on a Federation ship that had a cloaking device." Well, yes he has! He was abord the Enterprise-D during the events of "The Pegasus", when the ship used the illegal Federation phase cloak system to escape from an asteroid.

When Worf meets O'Brien and Bashir in the bar, O'Brien offers to play darts with him and Worf replies that he doesn't play games. Huh? Worf spent years playing poker on the Enterprise-D, a fact that O'Brien immediately points out to him! Why would Worf laim that he didn't play games? For that matter we also saw him on his way to play a game of Parrises Squares in "11001001".

Worf also acts a little oddly towards Dax and Kira appearing emerging from the holosuite dressed in medieval garb. People on the Enterprise-D dressed in odd costumes all the time to go play on the holodeck, including Worf, who for example dressed as a cowboy to play with his son in "A Fist Full Of Datas". Why is it suddenly embarrasing for him to see people in costume?

Great Moment :

The space battle - wow. I mean, WOW! Especially so when you consider that this episode was made without CGI - the entire battle with the Klingon fleet was done via model work. I cannot express sufficiently just how much kudos the behind the scenes folks deserve for their efforts in this episode.

Body Count :

Untold numbers. Probably well into the hundreds.

Factoid :

The original plan was for the end of Season 3 and beginning of season 4 to be a two part episode about Founders infiltrating Earth. The studio executives nixed the idea of a cliffhangar ending, which led to "The Adversary" ending Season 3 on a somewhat ominous note, without being a cliff-hangar as such. This necessitated reworking the Season 4 opening; since raings were falling the studio wanted something that would "shake things up" in the DS9 universe. The initial plan was to have Vulcan leave the Federation, but Ira Steven Behr suggested breaking up the Federation/Klingon alliance, since a Founder had stated in "The Die is Cast" that those two powers were the only real threat to the Dominion in the Alpha Quadrant. This led to the idea of bringing Worf onto the show, since his involvement in a Federation/Klingon conflict would make sense and the character was popular with fans. The original "Founders on Earth" idea would later be turned into the two parter "Homefront" and "Paradise Lost".

Michael Dorn's joining Deep Space Nine leads to Worf becoming the longest running character in all of Star Trek history, having served through eleven seasons (272 episodes in all), and four movies.

When Worf meets Dax, he says "Curzon's name is an honoured one among my people." She replies with a line in Klingon which is untranslated, leading Worf to reply "I suppose so." Dax said "Yeah, but I'm a lot better looking than he was."

More untranslated Klingon, between Martok and Gowron during the battle. Martok says "They fight like Klingons!" Leading Gowron to reply "Then they can die like Klingons! Destroy their shields! Prepare boarding parties!" Martok then says "I understand. All ships, concentrate fire on their shield generators."

And yet more! When the Klingon Drex is hassling Morn on the Promenade, Odo approaches and asks if he can help. Drex says something in Klingon, leading Garak to say "Actually, I'm not sure Constable Odo has a mother." Drex's line is "Does your mother let you talk to adult men?"

The original plan for this episode was to introduce several completely new Klingon warship designs. Alas, budgetary constraints led to the re-use of existing Klingon ship models along with the future Klingon ships from TNG's "All Good Things". One of the proposed Klingon designs would go on to be used as the basis of the retro Bird of Prey used in Enterprise, though.

The episode as filmed turned out to be a little too long, leading to some scenes being cut. One cosidered for deletion was the Garak/Quark root-beer scene. Producer Ronald D. Moore sucessfully fought to keep the scene in the episode; after the episode aired, the scene because a popular fan favourite because of it's wry 'outside look' at the Federation.

Martok introduces himself to Sisko by cutting his palm open and spilling some blood to demonstrate that he is not a Founder infiltrator. In the two parter "Homefront / Paradise Lost", Joseph Sisko points out that the blood test isn't reliable because a changeling could simply hold a quantity of real blood inside its body and dispense it as needed. Since we will learn in "Apocalypse Rising" that the Martok we see in this episode actually is a Founder infiltrator, Joseph was obviously correct - and thus, the blood tests we see performed throughout Deep Space Nine are entirely useless.

Plotline

When the Klingons launch an all out war against Cardassia, recently rocked by civil strife and revolution, Sisko decides to disobey Federation policy and intervene in the war for no apparent reason. Soon the Klingons launch a major attack on the station - but Sisko has a few surprises in store for them.